Reactive alloys, under which we understand here alloys with high concentration of alkali, alkali—earth as well as some rare-earth metals, are widely used in modern industry and technology. The scale of practical employment of these alloys can sufficiently grow if effective and safe ways of their treatment are found, in particular, methods of their forming, i.e. shaping an alloy into a required geometrical form with the preset dimensions. The forming process of this kind often includes an operation of incorporating the reactive metal with some auxiliary element, e.g. with a support, a shield, a heater, etc., as a result of which not just the material is produced, but already the end product.
Although the chemical activity of metals rapidly grows with the temperature and becomes extremely high after their transition into the liquid state it is the melt, which allows manufacturing of the products of any desired form with the lowest time and material consumption. There are many known methods of precision casting, however, the most suitable for mass production of standardized products is the method of controlled break up of laminar jet called monosize droplet spraying. In the given method the molten metal jet ejected through a capillary orifice breaks up into monosize droplets under the influence of regulated perturbations, which are generated by a piezoelectric transducer. Then the travelling droplets solidify in flight or on a target substrate.
In spite of the constructional variety of atomizers employing capillary instability of liquid jets [S. D. Ayers, D. J. Hayes, M. T. Boldman, D. B. Wallance, U.S. Pat. No. 5,772,106, Jun. 30, 1998; S. Q. Amster, J.-P. Delplanque, W.-H. Lai, E. J. Lavernia, Metall. Trans. B., Vol. 31 B, (2000) 1333-1344; Q. Liu, M. Orme, Proc. Instn. Mech. Engrs., Vol. 215, Part. B (2001) 1333-1355; S. Roy, Mono—size droplet production by the uniform—droplet spray process at high temperature—with Application to ASTM F75 and Ailicon (Dissertation), Northeastern University Boston, Mass., August, 2009], no atomizer, which would be suitable for disintegration of reactive melts, has been created yet.
Reactive alloys with their high chemical activity and volatility impose much stricter requirements to the technical equipment than usual metals. For this reason in the past the demand for active metals was satisfied with the help of redox reactions, where the active metal in a free form appears only as a product of exothermal reaction taking place in the powder mixture of the reducing agent with the chemicals containing a reactive component [D. Marelli, M. Mantovani, G. Urso, U.S. Pat. No. 6,873,102, Mar. 29, 2005; L. Cattoneo, S. Pirola, C. Maeda, A. Bonucci, U.S. Pat. No. 7,794,630, Sep. 14, 2010]. However, the given method has a number of disadvantages and is limited in applications.
The first attempt of dispersing liquid reactive alloys was undertaken in [K. Chuntonov, US Pat. Application 20060225817, Oct. 12, 2006], where for the production of high porosity intermetallic granules of calcium or strontium the technology of quenching of reactive droplets in liquid Ar with the further vacuum sublimation of the excess of Ca or Sr was used. Then this method was modernized for the production of dendritic porous granules based on lithium solid solutions. [K. Chuntonov, US Pat. Application 20100242727 Sep. 30, 2010].
However the method of quenching reactive droplets in the media of liquid coolant is applicable to a rather small number of products of a spherical form. In order to widen the product line of chemically active materials it is necessary to develop a universal method of dispersing reactive melts. Below the solution of this problem with the help of a new generator of single droplets is provided.